This is true when we have good knowledge about any particular game than we will place more high amount on risk as we will be more confident about this game. Both format of gambling are risky so we can say this gambling is any format is much risky.
First of all we can not say like that about everyone!
If someone is very good trader for him less risky will be trading. If someone is good poker player for sure he will win much more playing poker than when hw will trade.
For professionals in their field, it will ba always profitable.
For traders, also imprtant is what they trade! If that's are altcoins, it is very high risk market, so in my opinion profesional poker playing is less risky than trading altcoins.